While eating, a guy in my roommate's Spanish class comes up to us to ask my roommate if he can borrow his quizzes from the class.  After the guy leaves (and is far enough away) I tell my roommate he should make a copy of the quiz and white out all the answers and replace them with wrong answers.  
 
The wheels in his head immediately began turning and he came up with plenty of ideas for this.  An example: Writing in Spanish the guy turning in the make-up quiz is cheating.  Apparently he's really behind in the class, he probably won't check the answers himself to see if they're correct.
 
I'm not sure if I should be happy or disturbed by this.  For one, the guy IS cheating, should he be taught a lesson?  But...the potential of my roommate becoming an actual troll isn't setting well in my head.
 
EDIT:  Since nobody takes the time to read comments.  Roommate decided to give the guy the exam with unaltered (not changed) answers.